THE FREQUENCY CHARACTERISTICS OF WARM AND COLD EPISODES IN THE NIÑO REGIONS

On the basis of NOAA/CPC data of sea surface temperature anomaly in the Niño regions during Jan. 1950 –C Dec. 2003, the wavelet power spectrum of SST were studied with significance and confidence testing at different scales in this paper. It shows that the SST are provided with multi-time scales structure nested one another, and vary on scales of 2 –C 7 years, 8 –C 20 years and >30 years. The most significant variation of the warm and cold episodes is in the 4-year band of period. The power, frequency structure and confidence of the same episode are different in different Niño regions. The intensity of oscillations is increasing at low frequency bands and decreasing at high frequency bands from east to west in the Niño regions, especially after 1970.